When you see coupons in stores or get them in the mail (or wherever), they're not always ones you'd use. If you have a baby, pampers wipes coupons are probably like gold to you. I have no baby and I'd typically walk right past a pampers coupon if I ever saw one in stores.
With coupon train participation, you take every coupon you find. You keep what you can use and then send the others in the envelop to the next person on the train. If I'm the person before you on the train (still assuming you have a baby), you're thrilled to get so many pampers coupons. When you take out $10 in coupons, you put in $10+ in your coupons, send it to the next person on the list and they then take out coupons you thought were useless but they needed.
In the title of a train it will say 'looking for riders' or something like that if it hasn't already left the station. A train takes 6-10 people, they are all written on a list and then the list is mailed with the coupons in an envelope. Once the list is made the train is closed.
Does that make sense?
In order to get on most trains, you need a trade rating. Unfortunately, we've had more than a couple new members sign up, join trains and then keep the entire train when it arrives an vanish off SC. The trade rating is a symbol for trust. The best way to get a trade rating before you get them on trains is to trade for coupons. On the left hand tool bar there is a link called 'coupon list'. There is also a sub forum of coupons called 'Canadian Coupons Trading and Discussion'. The coupon list will take you to long lists of regular coupons people have up for trade (50cents off bounce, 75cents off bread, etc.). The trading and discussion forum has more "high value coupons" such as $10 off Olay or Free LaCoupe Shampoo.
Either way, it's very difficult for a new person to have enough good coupons posted on their coupon list that they can make a successful coupon-for-coupon trade. It is likely that you'll need to trade SDM(shoppers drug mart) Optimum points, Stamps, Gift Cards (ex. $5 to Tim Hortons) or Canadian Tire money. It may sound a little backwards to pay for stamps or gift cards and trade them for coupons but you do make your money back. There are a lot of people (myself included) that will trade you an (mystery) envelope of $100 in coupons for $5-$10 in stamps or GCs. Even if you only use 25% of the coupons you've still made your money back 5x.
Once you've made a few trades and become more chatty on the message boards you'll be welcome on almost any train. You check the forum daily for a new train taking riders and ask if you can join. Usually, they ask you to private message them a request and your address, along with posting in the thread where they state that they are taking riders. Some trains have unique requirements (conductors only, must contribute at least one FPC, western providences only, etc.). Make sure you can meet all requirements before asking to join.